Seismic Behaviour Of Artificial Hinge Of Assembly Beam Column Joint

The assembled structures are widely used in practical projects.The common assembled structures are not connected well enough leading to poor structural integrity,especially under the effect of large earthquakes or aftershocks,which can lead to serious secondary disasters.Most of the research in recent years has focused on improving the seismic performance of beam-column joint,and there is less research on rapid repair after earthquakes.Therefore,in order to further promote and widely apply the assembled structure,there is an urgent need to study an economical and integral beam-column joint that can be repaired quickly.In this paper,an assembly beam-column joint with replaceable artificial hinge is proposed to address the above problems,and the following studies are done:（1）Two assembled beam-column joint and one cast-in-place reinforced concrete beam-column joint were subjected to low circumferential reciprocal loading tests to analyze their seismic performance.The results show that the assembled joint exhibit good hysteresis performance,and their hysteresis curves show a relatively full bow shape.Due to the weakening of artificial hinges to inhibit the development of concrete cracks,the stiffness degradation of assembled beam-column joint in the late loading period is significantly slower than that of cast-in-place beam-column joint.The equivalent viscous damping coefficientξ_eq=0.118～0.513for the assembled joint.the equivalent viscous damping coefficient of ordinary cast-in-place reinforced concrete is not less than 0.1,and the equivalent viscous damping coefficient of assembled joint is not less than that of ordinary reinforced concrete.The ductility coefficients of assembled joint are all in accordance with the range of values required by the code.The energy dissipation capacity and ductility derived from the hysteresis curves all meet the seismic performance index.（2）Three FEM models of assembly beam-column joint with replaceable artificial hinges were established under low cyclic reversed loading based on ABAQUS.The Clough model considering the load-bearing capacity degradation is selected for the reinforcement principal structure relationship,which can better reflect the degradation of the material properties and the bond-slip relationship between the reinforcement and concrete.By comparing the damage pattern,hysteresis curve and stiffness degradation performance,the finite element simulation results are verified to be in good agreement with the actual test.In addition,the paper analyzes the parameters of the thickness,length,energy-consuming plate and the connection between the hinge and the beam.The results show that:the appropriate increase of steel plate thickness is beneficial to improve the seismic performance of the joint;the assembled joint with T-shaped plates have the best load capacity but the worst ductility,and the assembled joint with non-dissipative plates and U-shaped plates have significantly improved ductility;the joint with T-shaped plates have the best joint stiffness and stiffness degradation rate,which is 11%higher than the assembled joint with non-dissipative plates and U-shaped plates.Strengthening the connection between artificial hinges and beams can effectively improve the seismic performance of the assembled joint.（3）Four finite element model of an assembly beam-column joint with replaceable artificial hinges and its frame structure under earthquake action is established based on Open Sees.In this paper,Beam-column joint element is used to simulate the core area of beam-column joint.The element simulates three failure modes for joint through three components.All three components are explained as followed:First of all,the zero-length bar slip element simulates the degradation of stiffness,strength caused by the bond slip of the beam and column longitudinal bar in the joint.Secondly,the zero-length cross-interface shear element simulates the degradation of the shear capacity of the peripheral cross-interface of joint.Finally,shear plate elements simulate the degradation of joint strength and stiffness caused by shear failure in the core area of the joint.In general,The joints’calculation results are relatively consistent with the actual test results.The modeling method is used for seismic response analysis of frame structure with high accuracy.The deformation of structures under different seismic wave intensities is concentrated in layers one to three,and the requirement for maximum inter-layer displacement angle is present in layer two.The maximum interlayer displacement angle did not exceed the limit of 1/50 under the action of three seismic waves which explained that the frame with this kind of joint meets the requirements of seismic design under the action of three seismic waves.